The umask is a process-wide value, so bind_unix_socket() races with file
creation in other Open vSwitch threads. This fixes the race.
The workaround for non-Linux systems is not ideal, but I do not know any
other general solution. I tested the workaround only on Linux.
CC: YAMAMOTO Takashi <yamam...@valinux.co.jp>
Signed-off-by: Ben Pfaff <b...@nicira.com>
---
lib/socket-util-unix.c | 35 ++++++++++++++++++++++++++++++-----
1 file changed, 30 insertions(+), 5 deletions(-)
diff --git a/lib/socket-util-unix.c b/lib/socket-util-unix.c
index 6b451d4..59b8160 100644
--- a/lib/socket-util-unix.c
+++ b/lib/socket-util-unix.c
@@ -23,6 +23,7 @@
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/un.h>
+#include <sys/wait.h>
#include <unistd.h>
#include "fatal-signal.h"
#include "random.h"
@@ -261,11 +262,35 @@ free_sockaddr_un(int dirfd, const char *linkname)
static int
bind_unix_socket(int fd, struct sockaddr *sun, socklen_t sun_len)
{
- /* According to _Unix Network Programming_, umask should affect bind(). */
- mode_t old_umask = umask(0077);
- int error = bind(fd, sun, sun_len) ? errno : 0;
- umask(old_umask);
- return error;
+ const mode_t mode = 0700;
+ if (LINUX) {
+ /* On Linux, the fd's permissions become the file's permissions. */
+ return fchmod(fd, mode) || bind(fd, sun, sun_len) ? errno : 0;
+ } else {
+ /* On FreeBSD and NetBSD, only the umask affects permissions. The
+ * umask is process-wide rather than thread-specific, so we have to use
+ * a subprocess for safety. */
+ pid_t pid = fork();
+
+ if (!pid) {
+ umask(mode ^ 0777);
+ _exit(bind(fd, sun, sun_len) ? errno : 0);
+ } else if (pid > 0) {
+ int status;
+ int error;
+
+ do {
+ error = waitpid(pid, &status, 0) < 0 ? errno : 0;
+ } while (error == EINTR);
+
+ return (error ? error
+ : WIFEXITED(status) ? WEXITSTATUS(status)
+ : WIFSIGNALED(status) ? EINTR
+ : ECHILD /* WTF? */);
+ } else {
+ return errno;
+ }
+ }
}
/* Creates a Unix domain socket in the given 'style' (either SOCK_DGRAM or
--
1.7.10.4
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